TW201638458A - Silencer - Google Patents

Abstract

A silencer 2 comprises an introducing damping compartment 10. The introducing damping compartment 10 comprises an introducing part 24, an expanding chamber 26, and a delivering part 16. The expanding chamber 26 communicates with the introducing part 24 and has the larger flow pass section than the flow pass section of the introducing part 24. The expanding chamber 26 has projections 32 formed in the aspect along the travel direction of the sound wave of which the resonance should be suppressed. The delivering part 16 communicates with the expanding chamber 26, has the smaller flow pass section than the flow pass section of the expanding chamber 26, and delivers a fluid in a different direction from the introducing direction of the fluid. Therefore, the resonance of the wave is weakened, a rise of the internal sound pressure of the silencer is suppressed, and a lowering of the silent effect is prevented.

Description

silencer

The present invention relates to a silencer.

It is known that large sound waves are generated in the exit space of the compressor. Attenuating these sonic systems is beneficial for various reasons of attenuation.

A silencer having such a sound wave attenuation function has been disclosed in, for example, Patent Document 1.

The muffler of Patent Document 1 includes an introduction pipe, a discharge pipe, and an expansion chamber that communicates with the above. In this muffler, a sharp change in impedance occurs due to a change in the cross section of the introduction pipe, the expansion chamber, and the discharge pipe, and the sound wave is reflected at the boundary to exhibit a noise cancellation effect.

However, in the muffler of Patent Document 1, the opposing surface in the direction in which the fluid is discharged from the expansion chamber resonates. Therefore, the sound pressure near the exit becomes high and the noise reduction effect is lowered.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Utility Model Publication No. 02-124214

The present invention has an object to improve the resonance of sound waves in a muffler and to enhance the problem of noise reduction.

According to the present invention, there is provided a muffler including an introduction attenuating portion, wherein the introduction attenuating portion includes: an introduction portion that introduces a fluid; and the communication portion that communicates with the introduction portion has a flow path cross section that is larger than a flow path cross section of the introduction portion, and An expansion chamber having a non-flat portion on a surface in which the sound wave of the resonance sound is suppressed; and a flow path cross-section that is smaller than a flow path cross-section of the expansion chamber, and is different from a direction in which the fluid is introduced. The direction deriving portion of the fluid is derived.

According to this configuration, the inner wall surface of the muffler is provided with a non-flat portion so that the resonance of the sound wave can be weakened, the rise of the internal sound pressure of the muffler is suppressed, and the noise reduction effect is prevented from being lowered. The muffler generates a sharp change in impedance due to a change in the cross section of the introduction portion, the expansion chamber, and the lead-out portion, and exhibits a noise cancellation effect due to reflection of the sound wave at the boundary. However, a sound wave of a given frequency causes a resonance of a given frequency in the expansion chamber. The sound waves of the frequency at which the resonance is caused are interfered by the uneven portion to suppress resonance. Therefore, it is possible to suppress an increase in the internal sound pressure and prevent a reduction in the noise cancellation effect.

It is preferable that the uneven portion has a convex portion.

The height of the convex portion is preferably a height that does not interfere with the flow path of the fluid when viewed from the direction in which the fluid is introduced.

According to this configuration, an increase in pressure loss can be prevented. When there is a convex portion in the flow path of the fluid, the pressure loss increases due to an obstacle to the flow. The height of the convex portion is set to be insufficient to interfere with the height of the flow path, so that an increase in pressure loss can be prevented.

The uneven portion may also include a recess.

According to this configuration, the concave portion is provided so that the resonance in the expansion chamber can be weakened like the convex portion, and the increase in the internal sound pressure of the muffler can be suppressed, and the noise reduction effect can be prevented from being lowered. Furthermore, the provision of the recesses increases the effect of the lateral branch.

The concave portion is preferably a hole portion and a closing plate that closes the hole portion.

According to this configuration, the concave portion can be realized with a simple configuration. Further, in the case where the attenuating portion is introduced by casting, the hole or the like can be used to discharge the sand or the like in the expansion chamber. Further, after the muffler is assembled and installed in a unit, a rod or the like can be inserted from the hole portion to contact each portion, and the state, operation, and the like of each portion can be confirmed.

The uneven portion may include a convex portion and a concave portion. Further, the height of the convex portion is preferably a height that does not interfere with the flow path of the fluid when viewed from the direction in which the fluid is introduced. Further, it is preferable that the concave portion is constituted by a hole portion and a closing plate that closes the hole portion.

a screw hole for fixing the aforementioned blocking plate is provided on the aforementioned convex The part is preferred.

According to this configuration, the thread can be sufficiently hung and fixed by bolts without thickening the thickness of the muffler body.

The area in which the uneven portion is formed is preferably half or less with respect to an area on the inner wall surface on which the uneven portion is formed, in which the uneven portion is not formed.

According to this configuration, the formation area of the uneven portion is set to be less than or equal to half of the non-formation area, so that the original frequency characteristic of the expansion chamber can be maintained. The original frequency characteristic of the expansion chamber refers to a silencing characteristic caused by interference of sound waves in a direction perpendicular to the inner wall surface on which the uneven portion is formed. When the formation area of the uneven portion exceeds a predetermined value, the uneven portion itself acts as a wall surface, so the original frequency characteristic of the expansion chamber is lost (changed).

It is preferable that a part of the uneven portion is provided at the center between the opposing faces forming the expansion chamber in the introduction direction of the fluid.

A part of the uneven portion is provided at a position centered between the opposing faces caused by the resonance, so that the resonance of the expansion chamber can be more effectively suppressed. Since the particle velocity is the fastest at the center between the opposing faces, the non-flat portion interferes with the particles having a fast particle velocity, so that a large noise-cancellation effect can be exhibited.

a plurality of attenuation portions disposed in a sound direction of the fluid flow direction, wherein the most upstream attenuation portion is the introduction attenuation portion, and the attenuation of the most downstream of the plurality of attenuation portions The portion discharge attenuating portion, wherein the discharge attenuating portion preferably includes a portion that communicates with an adjacent attenuating portion adjacent to the discharge attenuating portion a second intermediate communication portion that is disposed in the discharge attenuating portion, a valve portion that can block the second intermediate communication portion, and a biasing portion that elastically biases the valve portion toward a direction in which the second intermediate communication portion is closed a valve holding portion that can be detachably attached to a frame body including the plurality of attenuation portions, and a portion that is different from the valve holding portion, and that discharges the fluid from the discharge attenuating portion .

According to this configuration, since the valve portion is disposed inside the discharge attenuation portion which is the most downstream, the muffler can be closely configured. Further, a plurality of attenuation portions are disposed in the flow direction of the fluid, and an intermediate communication portion is provided in the partition portion between the attenuation portions, so that sound waves in a wide frequency range can be attenuated. Further, since the valve holding portion that closes the intermediate communication portion is provided in the valve holding portion of the casing, the backflow of the fluid can be prevented. Further, since the valve portion is provided in the valve holding portion that can be attached to and detached from the casing, and the discharge portion is provided in a portion other than the valve holding portion of the casing, the valve can be operated under the piping that does not remove the discharge portion. Department of maintenance. That is, it is possible to achieve a compact structure in which the sound of a wide frequency range is attenuated and the valve portion can be easily maintained to prevent backflow of the fluid.

According to the present invention, the inner wall surface of the muffler is provided with a non-flat portion so that the resonance of the sound wave can be suppressed, and the noise cancellation effect can be enhanced.

2‧‧‧Muffler

4‧‧‧Compressor body

6‧‧‧Spit out the flow path

8‧‧‧Muffler body (frame)

9‧‧‧ side wall

10‧‧‧Introduction of attenuation

12‧‧‧Adjacent attenuation

14‧‧‧Discharge attenuation

15‧‧‧ partition wall

16‧‧‧1st intermediate communication part (export part)

18‧‧‧2nd intermediate connection

20‧‧‧Departure

22‧‧‧ bolt

24‧‧‧Importing Department

26‧‧‧Expansion room

28‧‧‧The Department of Occlusion

30‧‧‧flat surface

32‧‧‧ convex part (non-flat part)

34a, 34b‧‧‧ opposite (wall)

35‧‧‧Expansion room

36‧‧‧Multiwell plate

38‧‧‧through holes

40‧‧‧Back air layer

42‧‧‧Exporting Department

43‧‧‧Expansion room

44‧‧‧ openings

46‧‧‧Cover (valve retention)

48‧‧‧ bolt

50‧‧‧ Valve Department

52‧‧‧ valve body

52a‧‧‧ front side section

54‧‧‧Mission

56‧‧‧End

58‧‧‧The other end

59‧‧‧Exporting

62‧‧‧ recess (non-flat part)

64‧‧‧ Hole Department

66‧‧‧Closed board

68‧‧‧ openings

70‧‧‧ great

72‧‧‧ screw holes

74‧‧‧ bolt

Fig. 1 is a schematic view showing a part of an apparatus to which a muffler according to a first embodiment of the present invention is applied.

Fig. 2 is a schematic longitudinal sectional view showing a muffler according to a first embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view of the flat surface and the convex portion of Fig. 2 as seen from the axial direction.

Fig. 4 is a schematic view seen from an inflow portion for an expansion chamber into which an attenuation portion is introduced.

[Fig. 5] A graph showing the decrement of the silencer according to the presence or absence of the convex portion.

Fig. 6 is a schematic longitudinal sectional view showing a muffler according to a second embodiment of the present invention.

Fig. 7 is a schematic cross-sectional view showing the flat surface and the concave portion of Fig. 6 as seen from the axial direction.

Fig. 8 is a view showing an example of the preparation of the occlusion plate of Fig. 6 .

Fig. 9 is a schematic longitudinal sectional view showing a muffler according to a third embodiment of the present invention.

Fig. 10 is a schematic cross-sectional view showing the flat surface, the convex portion, and the concave portion of Fig. 9 as seen from the axial direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in the following description, it is convenient to use the direction, position, etc. The terms (for example, "upstream side", "downstream measurement", etc.) are used to limit the technical scope of the present invention in order to facilitate the understanding of the invention. In addition, the following description is merely an exemplification of one embodiment of the present invention, and is not intended to limit the present invention, its application, or its use.

(First embodiment)

Fig. 1 is a schematic view showing a part of a device (screw compressor) to which the muffler 2 of the first embodiment is applied. The muffler 2 is a flow path in which a sound wave is propagated by superimposing a flow of a fluid. In the present embodiment, the muffler 2 is disposed on the discharge flow path 6 of the screw compressor main body 4 in order to mute the sound generated by the flow of the compressed air which is a fluid.

The configuration of the muffler 2 of the first embodiment will be described with reference to Fig. 2 .

Fig. 2 is a schematic longitudinal sectional view showing the muffler 2 of the first embodiment. As shown in Fig. 2, the muffler 2 is formed such that compressed air (fluid) flows inside, and the muffler body (frame) 8 is formed in a cylindrical shape centering on the axis P. The muffler body 8 has a side wall 9 that forms a cylindrical side surface, and an upstream end portion of the side wall 9 is closed by a circular closing portion 28, and a circular opening is formed at a downstream end portion of the opposite side. Part 44. The opening 44 is closed by a detachable lid portion (valve holding portion) 46. The lid portion 46 has an outer shape substantially the same shape as the opening portion 44 of the muffler body 8, and is fastened to the muffler body 8 by bolts 48.

The muffler body 8 is separated from the blocking portion 28 by a predetermined distance (for example, 1/3 of the total length) in the direction of the axis P (the left side in the drawing). A partition wall 15 projecting from the side wall 9 toward the radially inner side is provided. The partition wall 15 is formed with a first intermediate communication portion (derivation portion) 16 which is a circular through hole concentric with the axis P when viewed in the direction of the axis P. Further, between the partition wall 15 and the opening portion 44, an annular partition portion 20 is disposed concentrically with the shaft P. The partition portion 20 is a second intermediate communication portion 18 having a circular through hole that is concentric with the shaft P when viewed in the direction of the shaft P, and is detachably fastened to the muffler body 8 by bolts 22.

In the muffler body 8, the attenuation portion 10, the adjacent attenuation portion 12, and the discharge attenuation portion 14 are provided in order from the upstream side toward the downstream side in the direction of the axis P. The introduction attenuation unit 10 and the adjacent attenuation unit 12 are partitioned by the partition wall 15 and share the first intermediate communication portion 16 that communicates with each other. Further, the adjacent attenuation portion 12 and the discharge attenuation portion 14 are partitioned by the partition portion 20, and the second intermediate communication portion 18 that communicates with each other is shared. Further, in the present embodiment, the muffler body 8 is formed in a cylindrical shape, but may be formed in a polygonal tube shape.

The introduction attenuation unit 10 is disposed at the most upstream, and includes a circular introduction portion 24 that introduces compressed air in a direction orthogonal to the axis P, and an expansion chamber 26 that communicates with the introduction portion 24 and the first intermediate communication portion 16. The introduction portion 24 is a muffler main body 8 disposed other than the end portion of the expansion chamber 26 in the direction of the axis P, that is, disposed on the side wall 9. The expansion chamber 26 is defined by the inner surfaces of the side wall 9, the closing portion 28, and the partition wall 15, and has a flow path cross section larger than the flow path cross section of the introduction portion 24 and the first intermediate communication portion 16. The inner wall surface of the closing portion 28 is formed with a flat surface 30 orthogonal to the axis P and a direction from the flat surface 30 toward the axis P (left in the drawing) A convex portion (non-flat portion) 32 of a convex shape.

3 is a schematic cross-sectional view of the flat surface 30 and the convex portion 32 as seen from the direction of the axis P. As shown in Fig. 2 and Fig. 3, in the present embodiment, four columnar convex portions 32 are disposed. The four convex portions 32 are centered on the axis P and are 3/4 with respect to the inner diameter of the expansion chamber 26. The circumference of the diameter is arranged at equal intervals on the circumference. In the arrangement of the convex portions 32 on the inner wall surface of the closing portion 28, the formation area of the convex portion 32 is half or less with respect to the non-formation area of the convex portion 32 (that is, the area of the flat surface 30). The convex portion 32 is disposed.

As long as the area relationship is satisfied, it is not limited to the configuration shown in FIG. 3, and may be configured arbitrarily. Preferably, the arrangement of the convex portions 32 is preferably such that a part of the convex portions 32 is disposed at the center of the opposing faces 34a and 34b in the vertical direction of FIG. 2 (the introduction direction of the compressed fluid in the introduction portion 24). This is because the particle velocity is fast in the vicinity of the center between the opposing faces 34a and 34b away from the wall faces 34a and 34b, so that a large interference effect can be expected. When the muffler main body 8 has a cylindrical shape as in the present embodiment, the opposing faces 34a and 34b are substantially one surface. In this case, the opposing faces 34a and 34b are shown in the expansion chamber 26. Upper and lower parts on the inner wall surface. In the present embodiment, it is preferable to arrange the convex portion 32 so as to include the cylindrical central axis P at the center of the upper portion and the lower portion of the inner wall surface of the expansion chamber 26.

Further, in the present embodiment, the four convex portions 32 are provided, but the number of the convex portions 32 is not limited thereto, and may be one or plural. The shape of the convex portion 32 is also not limited to a cylindrical shape, and may be, for example, A polygonal or annular cylinder or cone of a triangle, a quadrangle or the like.

4 is a schematic view seen from the introduction portion 24 for the expansion chamber 26 into which the attenuation portion 10 is introduced. As shown in FIG. 4, the height of the convex portion 32 (the convexity in the direction of the axis P) is defined so as not to interfere with the compressed air introduced from the introduction portion 24. That is, when the direction in which the compressed air is introduced from the introduction portion 24 is seen, the circular shape of the introduction portion 24 does not interfere with the rectangular shape of the convex portion 32. In the present embodiment, the height of the convex portion 32 is set to about 1/5 with respect to the length of the axis P of the expansion chamber 26.

Further, in the present embodiment, the heights of the four convex portions 32 are the same height, but the height of the convex portion 32 may be different for each convex portion 32 as long as it does not interfere with the compressed air introduced from the introduction portion 24. The height may be the same height of the plurality of convex portions 32. Further, the convex portion 32 is preferably integrally formed with the muffler body 8, but may be formed in a different shape, and the material thereof is not particularly limited. Further, the convex portion 32 is disposed only on the inner wall surface of the closing portion 28 (the end portion of the muffler 2), but is also disposed on the side of the first intermediate communication portion 16 facing the expansion chamber 26 that is introduced into the attenuation portion 10 The face is preferred. The reason is that further noise reduction effects can be expected.

Referring to Fig. 2, adjacent attenuation portion 12 is disposed adjacent to introduction attenuation unit 10 and discharge attenuation unit 14. In other words, the adjacent attenuation unit 12 is disposed between the introduction attenuation unit 10 and the discharge attenuation unit 14. The adjacent attenuation unit 12 includes an expansion chamber 35 that communicates with the first intermediate communication portion 16 and the second intermediate communication portion 18 in the direction of the axis P. The expansion chamber 35 adjacent to the attenuation portion 12 is defined by the inner surfaces of the side wall 9, the partition wall 15, and the partition portion 20, and has a ratio of the first intermediate communication portion 16 and the second intermediate portion. A cross section of the flow path in which the flow path section of the communicating portion 18 is large.

The expansion chamber 35 adjacent to the attenuation portion 12 is a sound absorbing chamber having a perforated plate 36. The porous plate 36 is formed of a metal such as iron or aluminum, a synthetic resin or the like. The perforated plate 36 is disposed on the radially outer side of the first intermediate communication portion 16 and the second intermediate communication portion 18 so as to extend in the direction of the axis P between the first intermediate communication portion 16 and the second intermediate communication portion 18 . . That is, the perforated plate 36 divides the expansion chamber 35 in the radial direction. A plurality of through holes 38 through which the compressed air passes through the perforated plate 36 extend in the direction of the axis P. A back air layer 40 is formed in a space radially outward of the porous plate 36 of the expansion chamber 35 and radially inward of the muffler body 8.

The porous plate 36 having the through holes 38 and the back air layer 40 attenuate the pressure due to the viscous friction between the medium (air or the like) in which the sound waves are generated in the through holes 38 and the inner wall surface. Further, pressure decay due to the vortex generated when the medium is ejected from the through hole 38 also occurs. Thereby, the sound absorbing effect is exerted. In particular, in terms of pressure attenuation due to viscous friction with the inner wall surface, the effect is large for the resonance frequency, and the resonance frequency can be determined by the thickness of the back air layer 40, the cross-sectional area of the through hole 38, the aperture ratio, The plate thickness of the perforated plate 36 is arbitrarily designed. In the present embodiment, the porous plate 36 and the back air layer 40 are configured, but a sound absorbing material made of a porous material such as glass wool or rock wool may be used instead. In addition, when the use environment is high temperature, a metal fiber material such as iron or stainless steel may be used.

Referring to Fig. 2, the discharge attenuating portion 14 is disposed at the most downstream, and has a circular row that discharges compressed air in a direction orthogonal to the axis P. The outlet portion 42 and the expansion chamber 43 that communicates with the discharge portion 42 and the second intermediate communication portion 18. The discharge portion 42 is a muffler main body 8 disposed other than the end portion of the expansion chamber 43 in the direction of the axis P, that is, disposed on the side wall 9. The expansion chamber 43 of the discharge attenuating portion 14 is defined by the inner surfaces of the side wall 9, the partition portion 20, and the lid portion 46, and has a flow larger than the flow path cross section of the discharge portion 42 and the second intermediate communication portion 18. Road profile. A valve portion 50 that can close the second intermediate communication portion 18 is provided in the lid portion 46. Further, in the present embodiment, the direction in which the compressed air is discharged in the discharge portion 42 is formed in a direction orthogonal to the axis P, but the direction of the lead is not limited thereto, and may be derived in a direction inclined with respect to, for example, the axis P.

The valve unit 50 includes a valve body 52 and a biasing member 54. The valve portion 50 is disposed coaxially with the shaft P. The front end side portion 52a of the valve main body 52 in the direction of the shaft P presses the second intermediate communication portion 18 so that the second intermediate communication portion 18 can be closed. The valve portion 50 has one end 56 fixed to the lid portion 46 and the other end 58 fixed to the valve body 52. In the state in which the cover member 46 is attached to the opening 44 of the muffler body 8, the biasing member 54 elastically biases the valve body 52 in the direction of the axis P, and closes the second intermediate portion by the valve body 52. The size of the communication portion 18.

Next, the action of the muffler 2 of the first embodiment will be described.

Referring to Fig. 1 and Fig. 2, when the screw compressor is actuated, compressed air is discharged from the discharge port 59 of the screw compressor main body 4 toward the discharge flow path 6, and the compressed air is introduced into the discharge unit 24 from the introduction portion 24 in the direction orthogonal to the axis P. Device 2. Therefore, the sound waves generated in the exit space of the compressor can be Attenuation, can be silenced. The compressed air introduced from the introduction portion 24 to the expansion chamber 26 is curved in the direction of the axis P in the expansion chamber 26, and flows from the first intermediate communication portion 16 to the adjacent attenuation portion 12.

When the introduction portion 24 is introduced into the expansion chamber 26, the cross-sectional area of the flow path of the compressed air is increased. That is, the impedance changes abruptly, so that the acoustic wave is reflected and attenuated inside the introduction attenuation unit 10. Specifically, the boundary between the introduction portion 24 and the expansion chamber 26 and the boundary portion between the first intermediate communication portion 16 and the expansion chamber 26 are reflected and attenuated. In this manner, the expansion chamber 26 is provided to vary the cross-sectional area of the flow path so that the sound generated when the compressed air is circulated can be attenuated. The introduction attenuation unit 10 of the present embodiment is a low-frequency side attenuation unit that attenuates sound waves in a low-frequency region.

Further, the introduction of the attenuation portion 10 is provided with the convex portion 32 on the inner wall surface of the closing portion 28 so that the resonance of the sound wave can be weakened, and the increase in the internal sound pressure of the muffler 2 can be suppressed, and the noise reduction effect can be prevented from being lowered. In general, in the case of the muffler 2, the compressed air introduced from the introduction portion 24 resonates at a predetermined frequency between the opposing faces 34a and 34b of the expansion chamber 26. The resonance of the predetermined frequency occurs when the half-wavelength 1/2λ of the wavelength λ of the sound wave coincides with the distance between the opposite faces 34a, 34b or the integral multiple, and the noise reduction effect is lowered. In the present embodiment, the convex portion 32 interferes with the sound wave of the frequency at which the resonance is caused, so that resonance can be suppressed. Therefore, it is possible to suppress an increase in the internal sound pressure and prevent a reduction in the noise cancellation effect.

When the convex portion 32 is present in the flow path of the compressed air, the pressure loss increases due to the obstacle to the flow. In order to prevent this, the height of the convex portion 32 is set to be insufficient to interfere with the height of the flow path, so that Reference can be made to the increase in pressure loss (see Figure 4 for reference).

Further, on the inner wall surface of the closing portion 28, the formation area of the convex portion 32 is defined to be less than or equal to half of the non-formation area (that is, the area of the flat surface 30) (refer to FIG. 3), so that the original frequency characteristic of the expansion chamber 26 can be maintained. . The original frequency characteristic of the expansion chamber 26 is a noise reduction characteristic due to interference of sound waves in the direction of the axis P. When the area where the convex portion 32 is formed exceeds a predetermined value, the convex portion 32 itself acts as a wall surface, so that the original frequency characteristic of the expansion chamber 26 is lost (changed).

Further, when a part of the convex portion 32 is provided at a position centered between the opposing faces 34a and 34b in the vertical direction due to resonance, the resonance of the expansion chamber 26 can be more effectively suppressed. Since the particle velocity is the fastest at the center between the opposing faces 34a and 34b, the convex portion 32 interferes to cause a large noise cancellation effect.

Fig. 5 is a graph showing the decrement of the muffler according to the presence or absence of the convex portion 32. As shown in FIG. 5, the convex portion 32 is provided so that the resonance frequency is weakened in the frequency at which the expansion chamber 26 resonates (1250 Hz and 2500 Hz), and the volume is decreased.

Referring to Fig. 2, the compressed air flowing in from the first intermediate communication portion 16 is adjacent to the attenuation portion 12, and passes through a plurality of through holes 38. In this case, the pressure due to the viscous friction between the compressed air and the inner wall surface generated in the through hole 38 is attenuated, and the pressure due to the vortex generated when the compressed air is ejected from the through hole 38 is further attenuated, so that the sound absorbing effect is exhibited. Thereafter, the compressed air in the region of the back air layer 40 is returned to the inside of the perforated plate 36 through a plurality of through holes 38, and merges from the second intermediate portion. 18 is compressed air that flows into the attenuation portion 14. The adjacent attenuation unit 12 of the present embodiment is a high-frequency side attenuation unit that attenuates sound waves in a high-frequency region. In particular, since the acoustic wave system in the high-frequency region passes through in a beam shape, a structure in which the compressed air advances in one direction may not be able to obtain a sufficient noise cancellation effect. The introduction of the attenuation portion 10 changes the direction of the flow path so that the direction of the sound can be changed, so that the sound wave is incident on the porous plate 36 at an angle. Thereby, even a high frequency sound can be reduced.

The compressed air in which the sound waves of the low frequency region and the high frequency region are attenuated by the second intermediate communication portion 18 is pressed against the biasing force of the biasing member 54 to press the valve body 52 of the valve portion 50 toward the opening portion 44 side. The expansion chamber 43 of the discharge attenuating portion 14 having a large cross-sectional area of the flow path flows in.

The compressed air that has flowed in from the second intermediate communication portion 18 in the discharge attenuating portion 14 is introduced into the introduction of the attenuating portion 10 as compressed air, and in particular, the sound wave in the low frequency region is reflected and attenuated inside the discharge attenuating portion 14. In this way, the cross-sectional area of the flow path is changed so that the sound waves generated when the compressed air is generated and propagated downstream can be attenuated. Therefore, the discharge attenuating portion 14 is a low-frequency side attenuating portion that attenuates the sound waves in the low-frequency region. Further, the compressed air is bent in a direction orthogonal to the direction of the axis P in a direction in which the direction of the axis P flows, and is led out from the discharge portion 42.

According to this configuration, since the valve portion 50 is disposed inside the discharge attenuation portion 14 which is the most downstream, the muffler 2 can be closely configured. Further, a plurality of the attenuation portions 10, 12, and 14 are disposed in the flow direction of the compressed air, and the first intermediate communication portion 16 and the second intermediate connection are provided therebetween. The through portion 18 is such that the sound waves of a wide range of frequency regions can be attenuated. Further, the valve holding portion 46 of the muffler body 8 is provided with the valve portion 50 that can close the second intermediate communication portion 18, so that the reverse flow of the compressed air can be prevented. Further, the valve portion 50 is provided in the valve holding portion 46 that can be detachably attached to the muffler body 8, and the discharge portion 42 is provided in a portion other than the valve holding portion 46 of the muffler body 8, so that it can be discharged without being discharged. Maintenance of the valve portion 50 is performed under the piping downstream of the portion 42. That is, it is possible to achieve a compact structure in which sound waves in a wide frequency range are attenuated and maintenance of the valve portion 50 capable of preventing backflow of compressed air can be easily performed.

(Second embodiment)

Fig. 6 is a longitudinal sectional view showing the muffler 2 of the second embodiment. The muffler 2 of the present embodiment has a configuration other than the portion related to the end portion of the attenuation portion 10 as in the first embodiment of Fig. 2 . Therefore, the same components as those in the configuration shown in FIG. 1 will be denoted by the same reference numerals and will not be described.

As shown in FIG. 6, the muffler 2 of the second embodiment forms a concave portion (non-flat portion) 62 and a flat surface 30 at an end portion of the expansion chamber 26 of the attenuation portion 10 in the direction of the axis P. The recessed portion 62 is constituted by a circular hole portion 64 that penetrates the muffler body 8 and a closing plate 66 that closes the hole portion 64. Therefore, the end portion of the direction in which the axis P of the attenuating portion 10 is introduced does not have the closing portion 28 as in the first embodiment, and has an opening portion 68 that is opened by the hole portion 64.

The concave portion 62 is provided so as to be convex as in the first embodiment 32 weakens the resonance in the expansion chamber 26, suppresses an increase in the internal sound pressure of the muffler 2, and prevents a reduction in the noise cancellation effect. Further, the provision of the recess 62 makes it possible to increase the effect of the lateral branch.

Further, the concave portion 62 is constituted by the hole portion 64 and the closing plate 66, so that the sealing plate 66 can be removed from the hole portion 64 and the sand or the like in the charging chamber 26 can be discharged from the hole portion 64 when the muffler body 8 is manufactured by casting. In addition, after the muffler 2 is assembled and installed in a unit, the rod 70 or the like can be inserted from the hole portion 64 and contacted with each portion. For example, the state, operation, and the like of the valve portion 50 can be confirmed (see FIG. 7).

Figure 8 is a schematic cross-sectional view of the flat surface 30 and the recess 62 of Figure 6 as seen from the direction of the axis P. As shown in FIGS. 6 and 8, the concave portion 62 is disposed concentrically with the shaft P at the center between the opposing faces 34a and 34b of the expansion chamber 26 in the vertical direction (the direction in which the introduction portion 24 introduces the fluid). In the arrangement of the concave portions 62 on the inner wall surface of the opening portion 68, the formation area of the concave portion 62 is such that the concave portion is disposed half or less with respect to the non-formation area of the concave portion 62 (that is, the area of the flat surface 30). 62.

Further, the arrangement of the concave portions 62 is not limited to the arrangement shown in FIG. 7 as long as the area relationship is satisfied, and may be arbitrarily arranged. However, it is preferable that a part of the recessed portion 62 is disposed at the center between the opposing faces 34a and 34b of the expansion chamber 26 as in the present embodiment. Further, in the present embodiment, one recessed portion 62 is provided, but the number of the recessed portions 62 is not limited thereto, and may be one or plural. The shape of the recess 62 is also not limited to a circular shape, and may be, for example, a polygonal shape or a ring such as a triangle or a quadrangle. Columnar or tapered.

(Third embodiment)

Fig. 9 is a longitudinal sectional view showing the muffler 2 of the third embodiment. The muffler 2 of the present embodiment has a configuration other than the portion related to the end portion of the attenuation portion 10 as in the first embodiment of Fig. 2 . Therefore, the same components as those in the configuration shown in FIG. 1 will be denoted by the same reference numerals and will not be described.

As shown in FIG. 9, the muffler 2 of the third embodiment has a convex portion (non-flat portion) 32 and a concave portion (non-flat portion) 62 in the introduction attenuation portion 10. The recessed portion 62 is constituted by a circular hole portion 64 that penetrates the muffler body 8 and a closing plate 66 that closes the hole portion 64. Therefore, the end portion of the introduction of the attenuating portion 10 does not have the closing portion 28 as in the first embodiment, and the opening portion 68 that is opened by the hole portion 64 as in the second embodiment.

As described above, the portion in which the introduction of the attenuation portion 10 suppresses resonance can be a combination of the convex portion 32 and the concave portion 62. The reason is that when the convex portion 32 and the concave portion 62 are combined, as in the case of the convex portion 32 of the first embodiment and the concave portion 62 of the second embodiment, the sound waves that resonate in the expansion chamber 26 can be interfered to suppress the resonance.

Inside the convex portion 32, a screw hole 72 for fixing the blocking plate 66 is provided. According to this configuration, the thread can be sufficiently hung and fixed by the bolt 22 without thickening the thickness of the muffler body 8. Further, the height of the convex portion 32 (the convexity in the direction of the axis P) is defined as the compressed air introduced from the introduction portion 24 without interfering with the first embodiment.

FIG. 10 is a schematic cross-sectional view of the flat surface 30, the convex portion 32, and the concave portion 62 of FIG. 9 as seen from the direction of the axis P. As shown in FIGS. 9 and 10, the concave portion 62 is disposed concentrically with the shaft P at the center between the opposing faces 34a and 34b of the expansion chamber 26 in the vertical direction. The arrangement area of the convex portion 32 and the concave portion 62 on the inner wall surface of the opening portion 68 is such that the formation area of the convex portion 32 and the concave portion 62 is a non-formed area with respect to the convex portion 32 and the concave portion 62 (flat surface 30) The convex portion 32 and the concave portion 62 are disposed such that the area is half or less.

Further, the arrangement of the convex portion 32 and the concave portion 62 is not limited to the arrangement shown in FIG. 10 as long as the area relationship is satisfied, and may be arbitrarily arranged. Among them, it is preferable that a part of the convex portion 32 or the concave portion 62 is disposed at the center between the opposing faces 34a and 34b of the expansion chamber 26. Further, in the present embodiment, four convex portions 32 and one concave portion 62 are provided, but the number of the convex portions 32 and the concave portions 62 is not limited thereto, and may be one or plural. The shape of the convex portion 32 and the concave portion 62 is not limited to a circular shape, and may be, for example, a polygonal shape such as a triangle or a quadrangle or an annular columnar or tapered shape.

Further, in the first to third embodiments, the convex portion 32 or the concave portion 62 is disposed on the surface along the introduction direction of the compressed air, but the arrangement is not limited thereto, and the traveling direction of the sound wave along the resonance should be suppressed. The face is fine. Therefore, for example, it may be a surface that faces the direction of introduction (opposing surfaces 34a and 34b).

Further, in the first to third embodiments, three methods including the introduction attenuation unit 10, the adjacent attenuation unit 12, and the discharge attenuation unit 14 will be described. The muffler 2 of the attenuation unit can be expected to have a muffling effect even if it is only introduced into the attenuation unit 10, for example. Therefore, it is not necessary to have a plurality of attenuation sections, and the number of attenuation sections may be one.

In the above-described embodiment, the compressor is described as an example. The muffler 2 may be incorporated in, for example, an automobile, a railway vehicle, a ship, or the like, which includes an engine.

2‧‧‧Muffler

8‧‧‧Muffler body (frame)

9‧‧‧ side wall

10‧‧‧Introduction of attenuation

12‧‧‧Adjacent attenuation

14‧‧‧Discharge attenuation

15‧‧‧ partition wall

16‧‧‧1st intermediate communication part (export part)

18‧‧‧2nd intermediate connection

20‧‧‧Departure

22‧‧‧ bolt

24‧‧‧Importing Department

26‧‧‧Expansion room

28‧‧‧The Department of Occlusion

30‧‧‧flat surface

32‧‧‧ convex part (non-flat part)

34a, 34b‧‧‧ opposite (wall)

35‧‧‧Expansion room

36‧‧‧Multiwell plate

38‧‧‧through holes

40‧‧‧Back air layer

42‧‧‧Exporting Department

43‧‧‧Expansion room

44‧‧‧ openings

46‧‧‧Cover (valve retention)

48‧‧‧ bolt

50‧‧‧ Valve Department

52‧‧‧ valve body

52a‧‧‧ front side section

54‧‧‧Mission

56‧‧‧End

58‧‧‧The other end

P‧‧‧ axis

Claims (12)

A muffler includes an introduction attenuating portion that attenuates the sound wave, and the introduction attenuating portion includes an introduction portion that introduces a fluid, and has a flow path cross section that is larger than a flow path cross section of the introduction portion, and is along the introduction portion. An expansion chamber having a non-flat portion on a surface in which the direction of the sound wave of the resonance is suppressed; and a flow path cross-section that is smaller than a flow path cross-section of the expansion chamber, and is different from the introduction direction of the fluid The direction of the fluid is derived from the lead-out portion of the fluid. The muffler of claim 1, wherein the non-flat portion has a convex portion. A muffler according to the second aspect of the invention, wherein the height of the convex portion does not interfere with a height of a flow path of the fluid when viewed from a direction in which the fluid is introduced. A muffler according to claim 1, wherein the non-flat portion is provided with a concave portion. A muffler according to the fourth aspect of the invention, wherein the recessed portion is configured by a hole portion and a closing plate that closes the hole portion. The muffler of claim 1, wherein the non-flat portion includes a convex portion and a concave portion. The muffler of claim 6, wherein the height of the convex portion does not interfere with the height of the flow path of the fluid when viewed from the direction in which the fluid is introduced. The muffler of claim 6, wherein the concave portion is configured by a hole portion and a closing plate that closes the hole portion. The muffler of claim 8, wherein a screw hole for fixing the blocking plate is provided in the convex portion. The muffler according to any one of claims 1 to 9, wherein an area of the non-flat portion is an area of the inner wall surface on which the uneven portion is formed, and the non-flat portion is not formed. Less than half. The muffler according to any one of claims 1 to 9, wherein a part of the uneven portion is provided at a center between the opposing faces forming the expansion chamber in a direction in which the fluid is introduced. The muffler according to any one of claims 1 to 9, further comprising: a plurality of attenuation portions disposed in a sound direction of the fluid flow direction; wherein the attenuation portion is the most upstream among the plurality of attenuation portions In the introduction of the attenuation unit, the attenuation unit is the most downstream of the plurality of attenuation units, and the discharge attenuation unit is provided in a portion that is adjacent to the adjacent attenuation unit adjacent to the discharge attenuation unit. a middle communication portion; a valve portion that is disposed in the discharge attenuation portion and that can block the second intermediate communication portion; a biasing member that elastically biases the valve portion toward a direction in which the second intermediate communication portion is closed; and a valve holding portion that can be detachably attached to a frame body including the plurality of attenuation portions while holding the valve portion; The discharge portion of the fluid is derived from the discharge attenuating portion at a portion different from the valve holding portion.